Well, depends on what you mean with trading. Just buy and sell Bitcoins or do you want to do arbitrage trading? First option is very easy. You need some starting capital and buy Bitcoin if you believe that there will be an higher price in the future. There are a lot of Bitcoin trading sites. You need to find out the best one for you. Kraken.com is the one I mostly choose. If you want to do arbitrage trading, then you need to good (propritary) software which finds price differences and you need a much higher starting capital then for first option.